The manufacture of semiconductor devices requires a number of discrete process steps to create a packaged semiconductor circuit device from raw semiconductor material. The various processes, from the initial melt and refinement of the semiconductor material, the slicing of the semiconductor crystal into individual wafers, the fabrication stages (etching, doping, ion implanting or the like), to the packaging and final testing of the completed device, are so different form one another and specialized that the processes may be performed in different facilities in remote regions of the globe.
For example, the process of growing and refining a large semiconductor crystal (e.g., Si, GaAs or the like) may be performed by a foundry specializing in such crystal growth techniques. The resultant crystals may then be sold directly to a semiconductor manufacturer, either as large crystals, or as wafers, sliced from a large crystal.
The semiconductor manufacturer may then slice the semiconductor crystal into wafers, if the semiconductor material is not already in wafer format. The semiconductor manufacturer then fabricates semiconductor circuit devices (e.g., microprocessor, DRAM, ASIC or the like) on individual wafers, usually forming a number of devices on each wafer. The individual fabrication (or "FAB") processes include photolithography, ion implantation, and other associated FAB processes known in the art. Typically, the resultant semiconductor device is tested on the wafer during and after the FAB process.
Once the semiconductor devices have been fabricated and tested on the wafer, the wafer is sliced up into individual semiconductor chips and packaged. The packaging process includes mounting and wire-bonding the individual chips to chip carriers (e.g., PLCCs, DIPs, CER-DIPs, surface mount carriers or the like) and final testing of the resultant packaged semiconductor device. This packaging process is fairly labor intensive, and thus it may be desirable to perform the mounting, wire-bonding, and final testing at an offshore facility where labor rates may be cheaper. Once completed, the packaged semiconductor device may again be tested, and then labeled and shipped to customers through a distribution system.
One problem which arises in this prior art manufacturing technique, is that the various processes take place at different discrete locations. Thus, it is difficult to track a semiconductor device through the fabrication process, from single crystal to finished product. Such tracking may be necessary for quality control purposes in order to determine the causes of production problems which may result in low yields or circuit defects.
In present fabrication facilities, individual fabrication machines or computer aided manufacturing systems (CAM systems) may provide data regarding operating conditions during the fabrication process. Some of these data are intrinsic data, for example, lot numbers, device model numbers or the like. Other data may be extrinsic data, such as production test data, production conditions, or the like. In the various processes, the various lot numbers may be changed, thus making it difficult for a production engineer to track down and solve difficulties in the production process.
For example, a semiconductor crystal or wafers may be assigned a manufacturer's lot number and shipped to a FAB facility. The FAB facility may in turn divide these wafers into different lots of 25 to 50 wafers, each assigned a new and different lot number. Each of these new lots of wafers may be used in the manufacture of a particular model semiconductor device. These lots may further comprise wafers commingled from other received lots of semiconductor wafers. During different process steps in the FAB facility, new lot numbers may be assigned to a wafer of group of wafers.
In the final assembly facility, the wafers are sliced up into chips, which may be assigned yet again new lot numbers. Through the production process testing and manufacturing steps are performed, generating data for each semiconductor device. If a problem arises in the manufacture of the semiconductor, for example a low yield of usable semiconductor devices, a production engineer may wish to track the semiconductor devices to determine why the production problem existed, correct the problem if necessary, and intercept other semiconductor devices similarly affected before performing additional process steps or shipping the product to the consumer.
Some efforts have been made through CAM systems to set up shop floor control systems (e.g. WorkStream.TM. or the like) and gather data on semiconductor devices during manufacturing. However, in such a shop floor control system, the collection of engineering data has been a by-product of the need to manage the inventory in the factory and manage the factory itself.
Unfortunately, in the prior art, no such system existed for effectively tracking engineering data from the various facilities. Manually tracking engineering data is hampered by several problems. First, the multiple facilities, if provided with computerized data acquisition systems (e.g., CAM or the like) may utilize different systems within the facility, and each facility may have systems different from the other. Thus, the computer systems may be incompatible and not effectively interfaced with one another. In addition, the different systems generally collect data in different formats, and thus data from one system cannot readily be compared or merged with data from another system. Further, since different lot numbers may be assigned at different steps in the manufacturing process, it may be difficult for an engineer to effectively track a particular chip, group of chips, wafer, or group of wafers back though the process steps. Since many of these CAM processes utilize computer systems dedicated to the manufacturing process, the systems may be unsuitable or too engaged to be used for manually tracking the production process of a semiconductor device.
In addition to improving the production process, the ability to track production data for a semiconductor device may also be useful to a semiconductor manufacturer in enhancing the value of the semiconductor to the consumer. For many critical applications (e.g., military or the like), the consumer may require assurances that the quality control of the semiconductor device can be effectively traced at each step. Further, the consumer may require that each semiconductor be provided with its "lineage," including the data generated in the manufacture and testing of the semiconductor device.